Chaff is a radar countermeasure in which aircraft or other targets spread a cloud of small, thin pieces of aluminum, metalized glass fiber, plastic, or the like to reduce the signal-to-interference ratio and reduce the probability of detecting a target. Like noise, chaff may be modeled as Gaussian distribution. However, chaff is usually distributed in a localized region of a search window and its variance is usually much higher than noise.
Radar systems typically utilize constant false alarm rate (CFAR) detection algorithms to detect target returns against a background of noise or other interference. For example, in cell averaging CFAR (CA-CFAR), a threshold level is calculated by calculating a noise floor around a cell under test (CUT). U.S. Pat. No. 5,808,579 issued to Rademacher discloses a radar system using a cell averaging constant false alarm rate device and is incorporated by reference herein in its entirety. However, CA-CFAR is not effective to determine the presence of chaff because of an increased threshold estimate caused by chaff contribution in the CFAR window.
Ordered statistic CFAR (OS-CFAR) is generally used to detect targets by avoiding distributed clutter. Therefore, OS-CFAR cannot be used for the detection of a chaff cloud since it ignores disturbed clutter.
Accordingly, a system and method for detecting a chaff cloud and estimating the centroid of the chaff cloud are desirable.